Screen printed garments are usually printed on rotary or oval multi print head machines in which the garments mounted on pallets are moved about the periphery of the machine where there are a series of print heads, curing stations and a load and an unload station. Patents relating to these machines include U.S. Pat. Nos. 4,407,195, 4,934,263, 5,154,119. Machines vary in size up to 20 stations which means there are up to 18 printing or curing heads plus the load and unload station. The operator sets up each print station with the appropriate screen, color and print settings before the garments are loaded. Usually the garments are printed in all the colors required and cured in one revolution of the machine.
Because of the complexity of the machine operation computer based control has become common. U.S. Pat. Nos. 5,483,881 and 5,678,482 are typical examples of the control systems employed.
In some cases the printed colors need to be cured before the next color is applied. Machines may not have sufficient print stations to accommodate all the curing and printing steps required. This problem has been overcome by carrying out the printing operation in more than one revolution of the machine. The machine is loaded with garments and in the first revolution all the garments are printed at certain heads only the time between the printing heads allowing the ink to cure. On the next revolution printing occurs at another set of heads and as many as 8 or 9 revolutions may be required to print the garments.
U.S. Pat. No. 5,595,113 is one attempt to provide a central programmed controller to assist the operator in carrying out this multi revolution printing sequence. The controller is programmed to select a printing station in a particular revolution, to index a garment to the selected print station, to determine whether the item is present at the print station and when the printing operation is complete. The controller stores the print head settings for each revolution in different buffers in the memory. In order to program the controller it is necessary to sequentially enter the revolution number, whether a head is active or inactive, whether it is a flash or print head and whether the print has one or two passes. Each pallet holding a garment is tracked by the controller and each station counts from the beginning of each revolution until the count equals the number of garments. This can be a cumbersome program. If an error is made in setting out the entire sequence the program must be deleted and re-entered. The controller senses the end of the operation by checking if there are any active heads in the next cycle and if not, the present revolution is the last. This is indicated to the operator by an alarm when the final revolution is half over so that the operator can commence unloading. A problem with this type of operation is that all the garments must be loaded before the printing sequence can begin and all the garments must be unloaded before the next sequence can begin. This makes the multi revolution printing process much more time consuming and costly.
It is an object of this invention to simplify the control program for multi revolution printing and to reduce the time taken for entering and a program and operating the machine, to improve productivity.